A pilot employed by American Eagle was removed for his plane this morning by airport police after failing an alcohol breath test.

The unidentified captain was in the process of preparing Flight 4590 service from Minneapolis-St. Paul International Airport to LaGuardia for takeoff when "a witness smelled what they believed was alcohol" on his breath, according to airport spokesman Patrick Hogan.

It's unclear if passengers were on board at the time: The Star-Tribune says 53 passengers were on the aircraft, but the Associated Press reports that passengers had not yet boarded the plane.

Either way, the pilot exceeded the state's legal limit for pilots (.04 percent blood alcohol content), and was arrested on suspicion of being under the influence.

Formal charges are awaiting the results of blood test conducted at a nearby hospital.

American Eagle has a well-established substance abuse policy that is designed to put the safety of our customers and employees first. We are cooperating with authorities and conducting a full internal investigation. The pilot will be withheld from service pending the outcome of the investigation.